7. Overgrown Tree Zombie (Season 4, Episode 3: 'Isolation')

In the midst of Season Four's prison-plague, Hershel decides to go foraging for healing elderberries, claiming that everything is safe in the woods. Right, except for that one immobile walker who's been decomposing on the ground for so long that a tree has already started growing around him, roots and all. (Technically half a zombie, actually.) Without its legs, this not-to-able-to-go-walking dead got stuck in the muck long enough for a tree to consume it. Think about that – the zombie-apocalypse has lasted so long that trees are now growing around and through these reanimated bodies. [Shudder]